Structure and formation mechanism of phosphate conversion coating on die-cast AZ91D magnesium alloy

Zhou, Weiyi; Shan, Dayong; Han, En‐Hou; Ke, Wei

doi:10.1016/j.corsci.2007.08.007

Cited by 239 publications

(87 citation statements)

References 13 publications

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“…At low frequencies it is obvious that there is a decrease in the impedance, followed by an increase. This impedance decrease stands for the corrosion of the metal, and the subsequent increase indicates the deposition of corrosion products on the metal surface [8][9][10]. For all treated samples the Bode plots also show impedance at least one order of magnitude higher than that of an untreated sample.…”

Section: -Electrochemical Investigationsmentioning

confidence: 69%

“…Chemical species with a nobler potential can form a galvanic couple in which magnesium acts as an anode, and therefore its corrosion rate increases. This is one of the reasons why corrosion protection methods like plasma electrolytic oxidation [5][6][7], conversion coatings [8][9][10], polymeric coatings [11][12] and others are preceded by a cleaning procedure that may consist of a simple grinding and polishing process, blasting, or of chemical processes such as acid pickling.…”

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confidence: 99%

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Surface modification of magnesium alloy AZ31 by hydrofluoric acid treatment and its effect on the corrosion behaviour

Conceição¹,

Scharnagl²,

Blawert³

et al. 2010

Thin Solid Films

103

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Section: -Electrochemical Investigationsmentioning

confidence: 69%

mentioning

confidence: 99%

Surface modification of magnesium alloy AZ31 by hydrofluoric acid treatment and its effect on the corrosion behaviour

Conceição¹,

Scharnagl²,

Blawert³

et al. 2010

Thin Solid Films

103

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“…As seen in Figure 4d, the clusters are composed by many coarse hexagonal flake structural units of Mg(OH) 2 , presenting loose stacking structure. As reported in the references [22,23], the hexagonal flake structural unit is the basic form of Mg(OH) 2 stacking crystals. This kind of structural unit can be found all over the coatings, which covers both the α-Mg phase and the secondary phase of the substrate.…”

Section: Microstructure Characteristic Of the Coatingsmentioning

confidence: 99%

Effect of Synthesizing Temperature on Microstructure and Electrochemical Property of the Hydrothermal Conversion Coating on Mg-2Zn-0.5Mn-Ca-Ce Alloy

Guo

Song

Jiang

et al. 2016

Metals

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Mg(OH) 2 conversion coatings were formed on an Mg-2Zn-0.5Mn-Ca-Ce alloy via hydrothermal method at three different synthesizing temperatures (160, 170 and 180˝C). The effect of synthesizing temperature on microstructure and electrochemical property of the coatings were systematically studied. With increasing synthesizing temperature, the coating became thicker due to the faster reaction and deposition of Mg(OH) 2 on the α-Mg phase and secondary phases of the substrate Mg alloy. Internal micro-cracks were also generated in the higher-temperature synthesized coatings due to the increased shrinking stress, but the cross-cutting micro-cracks were suppressed. Benefiting from the improved barrier effect against penetration of corrosive medium, the higher-temperature synthesized thicker coating presented significantly enhanced electrochemical property and anti-corrosion efficiency in Hanks' solution.

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“…Para mejorar la resistencia a la corrosión del magnesio y sus aleaciones se han propuesto diferentes alternativas, entre las que cabe destacar los tratamientos de modificación superficial, que incluyen recubrimientos de conversión química [2][3][4][5][6][7][8] , anodizado [9] , electrodepósito de hidroxiapatita [1] , entre otros. Los tratamientos para generar recubrimientos de conversión química son conocidos por su bajo coste y simplicidad de operación.…”

Section: Introductionunclassified

Tratamientos químicos de conversión para la protección de magnesio biodegradable en aplicaciones temporales de reparación ósea

Carboneras¹,

Hernández-Alvarado²,

Mireles³

et al. 2010

REVMETAL

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ResumenEl presente estudio se desarrolló para mejorar la resistencia a la corrosión del magnesio puro, modificando su superficie mediante recubrimientos de conversión química. Se generaron capas de carbonato y fluoruro por inmersión en soluciones de NaHCO 3 al 9 % y de HF al 48 %, respectivamente. La resistencia a la corrosión de las muestras con recubrimiento se evaluó en comparación con la del sustrato desnudo mediante técnicas electroquímicas en una solución fisiológica (PBS). Los resultados obtenidos han mostrado que el recubrimiento de carbonato no es capaz de proteger de la degradación al sustrato de magnesio. Por el contrario, el recubrimiento de fluoruro ha demostrado aumentar, significativamente, la resistencia a la corrosión del magnesio en medio fisiológico. La alta compacidad y adherencia al sustrato metálico de la capa de MgF 2 generada mediante este sencillo tratamiento de conversión química confieren al recubrimiento buenas propiedades protectoras. Palabras claveMagnesio; Corrosión; Conversión química; Biomateriales. Chemical conversion treatments to protect biodegradable magnesium in applications as temporary implants for bone repair AbstractThe present study was developed to improve the corrosion resistance of pure magnesium by applying chemical conversion coatings. Carbonate and fluoride layers were generated by immersion in solutions of NaHCO 3 of concentration 9 wt.% and HF of concentration 48 wt.%, respectively. Corrosion resistance of the coated samples was evaluated in comparison with that of the uncoated substrate by electrochemical techniques in a physiological solution (PBS). Results have shown that the carbonate coating is not viable to be used for protecting magnesium against corrosion. On the contrary, the fluoride magnesium coating significantly increases the corrosion resistance of magnesium in physiological medium. The high compactness and adherence to the base metal of the MgF 2 layer produced by this simple chemical conversion treatment confer the protective properties to the coating. KeywordsMagnesium; Corrosion; Chemical conversion; Biomaterials. INTRODUCCIÓNLos materiales para implantes metálicos convencionales, como aceros inoxidables y aleaciones base titanio, tienen un papel importante en la reparación del tejido del hueso dañado. Si estos implantes permanecen en el organismo por largo tiempo siempre liberan cationes metálicos que pueden dañar la salud. Este problema puede resolverse utilizando implantes biodegradables. Los implantes biodegradables pueden disolverse gradualmente, absorberse o excretarse después de que el hueso se ha reparado. El magnesio y sus aleaciones son materiales biodegradables potenciales debido a su atractivo comportamiento biológi-co [1] : 1) el magnesio se degrada en los fluidos corporales por corrosión; 2) el magnesio no es tóxico y su exceso puede fácilmente ser excretado en la orina; 3) el magnesio puede estimular el crecimiento de nuevo tejido en el hueso, haciéndolo particularmente apropiado para aplicaciones ortopédicas; 4) la densidad,

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Structure and formation mechanism of phosphate conversion coating on die-cast AZ91D magnesium alloy

Cited by 239 publications

References 13 publications

Surface modification of magnesium alloy AZ31 by hydrofluoric acid treatment and its effect on the corrosion behaviour

Surface modification of magnesium alloy AZ31 by hydrofluoric acid treatment and its effect on the corrosion behaviour

Effect of Synthesizing Temperature on Microstructure and Electrochemical Property of the Hydrothermal Conversion Coating on Mg-2Zn-0.5Mn-Ca-Ce Alloy

Tratamientos químicos de conversión para la protección de magnesio biodegradable en aplicaciones temporales de reparación ósea

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